Casting-flask for dentists



CASTING FLASK FOR DENTISTS.

APPLlcAnoN FILED Nov. s, 1920.

Patented Feb. A22, 1921.v

2 SHEETS-SHEET l.

T. E. MOORE.

CASTING FLASK FOR DENTISTS.

APPLlcAnoN HLED Nov. s. 1920.

1,369,182V latentenv Feb. 22, 1921.

' 2 SHEETS-SHEET 2.

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THOMAS E. MOORE, or TOLEDO, OHIO, Assieivon aio-THE nANsOM a RAivnOLrn u COMPANY, or TOLEDO, onio, A CORPORATION lor OHIO. Y

CASTING-FLASK FOR DENTIS'IS.Y Y i Application led November 8, 1920. ',Serial No.` 422,435.

' To au 'whom it may concern:

Be it known that I, THOMAS E. MOORE, a citizen of the United States, and resident of Toledo, in the county of Lucas and State of Ohio, have invented a certain new and useful Improvement in Casting-Flasks for Dentists, of which the following is a full, clear, concise, and exact description, referencev being had to the accompanying drawings, forming a part of this specification.

My invention relates to certain improvements in casting asks of the type employed by dentists Vin casting plates, bridges, and other restorations.

f A dentist in casting a plate, bridge, or other restoration, makes a pattern in wax of the Y article to be cast, invests this pattern in an initially plastic and quick hardening composition, permits the investment to dry,

melts out, or otherwise dissipates, the wax,

and then causesV molten metal toV flow through sprues. (gates) to the mold cavity remaining after the wax has been dissipated. This. is the well-known .lost wax7 or cire perdue casting processthat has beenv used in various artsfor centuries.

l'n dentalk work, the investment is invariably placed in a iiask which serves to confine the investment, and to facilitate the application of the force which is employed to cause the molten metal to flow to the mold cavity.- The forces vemployed are usually centrifugal force, steam, air, or other gas pressure greater than atmospheric pressure, applied tothe molten metal to cause the same tobe Vforced into the mold *cavity7 or suction applied to the investment to cause the molten metal vtobe forced 'into themold cavity, by the pressure of the surrounding air. While the particular 'embodiment of my invention hereinafter described is particularly adapted for use in connection with a pressure casting machine, a suction machine or a combined pressure and suction machine, itv will nevertheless appear that certain features of my invention are applicable toV flasks intended for use in conL nection with casting machines of thecentriff ugalV or any other type.

The several'types of casting'flask now lin general u'se'by dentists are universally characterized by two shortcomings. First, it is a difficult matter to remove the invested casting from theask after the completion of the casting operation. This difliculty in.

removal is-q'uite serious when' the Ycasting Y is a plate or other comparatively large vrestoration. Second, thev investment when placed'iii the ordinary flask tends to prevent the ready escape of air from'the mold cavity when molten metal is forced into the mold cavity-the sluggish escape ofv air from the mold cavity seriously detracting from the faithfulness of reproduction of the waX- pattern.

The principal objects of the present iii-. vention areto overcome the aforesaid short! .comings ot the :commonly used dental cast# ing flask.

Other objects ef this invention Vwill appear as the followingjdescription progresses.`

i In the accompanying drawingsdillustratf Figure l isV aplan view partially in section illustrating Aa casting flask construction' embodying my invention; y

Fig. 2 is a sectionalviewtakenlon. line 2--2 ofFig. l, lookingin the directiony indi# p cated by'thearrows; A l t Fig. 3 is-a view in perspective'of the investment holder, or inner flask, the bottom plate for said investment holder" beingk shown separated from the members whichl provide the side walls thereof;

F ig. t's a view in" perspective illustrating `the details of the under side of the cover plate for the outer receptacle, and l Fig. 5 is atop plan'view which', by dotted lines, indicates the proper positions of the elements of the investmentv holder within the Vouter receptacle.

Similar characters ofrreference lrefer toy similar parts throughout the several views.V

Theapparatusfof my invention :consists of two principal parts, namely, the outer receptacle A, find the investment holder B.

not differ essentially from platev `casting iasks heretofore used by dentistsbut does embody certain improvements which render The receptacle A in its general outline doe-s it Vparticularly adaptable foruse in the comev f a binationof my invention. When viewedfin plan, the Ashape of the receptacle A `follows i roughly the general outline of a dental plate. lts side wall is imperforate, and itsbottom wall is also imperforate, 'except at its central portiom'where it is provided with a coii'i-Y paratively largeopening.; 10- The Opengf lOiis Vbounded by an annular flaiige 11',"the

lower edge vof this v:flange beingpreferably ground so that it will coperate with the bed plate (indicated in dotted lines at 1.2) I of any satisfactory dental casting'machine of the suction or combined suction and pressure type.

Receptacle A is provided with a removableone-piece Vcover 13, which is imperforate at allpoints, save its central portion where it is provided with a comparatively large openinglli. Opening 14 is bounded b an annular flange 15, the upperedge of w ich is preferably Vground so that it will coperate Vin aVwell-lrnown manner with the pressure head (indicated b dotted lines at 16) of any approved denta casting machine of the pressure or combined suction and pressure type. The coverpis provided with an annular shoulder 1"?,so that a clay crucible 18 (of the type shown and claimed in Laing Patent No. 1, 307, 299, dated `June 17, 1919) may be placed in the opening 1li, if desired. The cover is provided onrits under surface withvthree projections 19-19, which serve properly lto locate the cover onf the receptacle A. The cover is furthermore conformedtoprovide an annular convex surface 20, the purpose of which will presently appear. Y Y Y The investment holder B comprises two metal side members 21 -.21, which when joined together by removable pins 22-22 providea cage, the Ageneral shape of vwhich conforms to the inner contour of the side Vwall of receptacle A. VVPins. 22 coperate lwith hinge loops 23 formed integral with the ends ofthe members 21-21, as is clearly,

Vapertures 25-25, which collectively alTo'rd a-,path for air from the investment to the space between the investment holder B and receptacle A. The investment holder comprises a bottom plate 26, which is so shaped as to I'it snugly within the lower portion of the investment holder when vthe members 21-21 thereof are assembled as shown in Fig.. 3.' larly tov the members 21 and isv provided with upwardly projecting ribs 2Y-27, which are yformed by pressing the metalof the plate upwardly along lines diverging from the center of the plate.

In preparing to use the apparatus of my invention,vin making a dental casting, for instance, in making a plate the several elements ofV the investment holder B are prop- Y erlyk assembled and placed Within the recepl tacle A,`asr shown in Fig'. 2. A layer of plas- The plate 26. is perforated simi-v tic investment is now placed upon the investment holder bottom plate Y26, to a depth `f-substantially equal to the height of the ribs 227-27. The wax pattern indicated at 3() is now placed upon this layer of investment, and as many sprue formers 31 as may be required are properly inserted in the'pattern in a Well-known manner. The investment holder is then lilled with investment to substantially the depth shown in Fig. 2. The cover plate 13 of the lreceptacle Agis now placed in position, and, incase the Laing crucibleis employed, it is also now placed in the position shown in Fig. 2. Attention. is directed to the fact that the annular convex surface 20 of the cover plate 13 aids in spreading the plastic investment out against the wall of the outer receptacle A. when the cover is applied, thereby eliminating air pockets in the investment, and making a goed seal between the upper portion of the investment and the Wall of recepllilClO A. i Y v'i After the investment material hasv suf- {iciently dried, the sprue formers are' removed, and heat is applied to drive the wax out of the investment.

VThe flask is now placed in a suitable casting machine, metal is meltedin the Crucible 18, Vand the metal is forced downwardly through the sprues to the mold .cavity by proper manipulation of the casting machine.

Regardless of the type of machine that is employed it is necessary that the air within the mold vcavity be permitted to escape quickly when the molten metal goes down through the sprues to take its place. The numerous apertures in the investment holder Y B, forming part of the device V*of my invention, permit ready escape of the air from the mold cavity to the opening 10, and to the space between the investment holder and the.

outer receptacle. It will be seen that the channels caused by the formation of theA ribs 27-27 of the investment holder bot-V tom plate 26 afford direct communication between opening 10 and the open space bel tween the investment vholder and the 're-l ceptacle A. Thisarrangeinent is Vparticularly advantageous when the apparatus of my present invention is usedin connection with a casting machine of the suction type or of the combined suction and pressure type, because in either of these cases, suction applied through the opening 10` in the receptacle A not only acts positively to draw the molten metal down into the mold cavity,

but also acts positively to draw the moltenl metal out against the lateral margins of the mold cavity. After thecasting operation has been completed, it is a simple matter to remove the investment from the flask and the casting from the investment Without in any way injuring the casting. The investment holder B is taken out of the' receptacle a 1,369,1sa

A and one or both of the hinge pins 22 are` removed. When this has been done, it 1s a simple matter tof remove the investment holder from the'investment. The investment is now broken open and the casting.

vided with an imperforate vertical wall and a bottom having a central aperture therein, an investment holder comprising a perforated bottom plate and a vertical wall consisting of two perforated metal'members detachably connected together", the vertical wall and bottom plate of the investment holder resting upon Vthe bottom of the receptacle, the members constituting the vertical wall of the investment holder being provided at their upper edges with outwardy turned flanges which space the vertical wall of the investment holder from the receptacle and provide an air space between them.

2. Apparatus of the class describedv comprising in combinationV a receptacle provided with an imperforate'vertical wall and a bottom having a centralaperture therein, an investment holder comprising a perforated bottom plate and a vertical wall consisting of two perforated metal members detachably connected together, Vthe vertical wall and bottom plate of the investment holder resting upon the bottom of the receptacle, vthe members constituting the vertical wall of the investment holder being provided Vat their upper edges Vwith 011131 ing in the receptacle bottom and the air space between the receptacle and investment holder. v n 3. Apparatus of the class described comprising an investment holder'consisting of a perforated bottom plate and avertical wall comprising two detachably connected perforated metal members each of which is' provided at itsupper edge with an outwardy turned Hange.

4. Apparatus of the class described comprising an investment holder having a verti- "cal wall consisting of a plurality of detachably connected perforated sheet metal members, each of which is provided at its upper edge with an outwardly turned flange.

v5. Apparatus of the class described comprising an investment holder consisting. of i a perforated bottom plate and aperforated i verticalV wall outwardly flanged at its upper margin to space' said vertical wall from a. Vreceptacle within which the investment holder may be placed.

6. Apparatus, of the class described com-v .n

prising an investment holder having a vertical wall consisting of a pair ofperfo-Vv rated metal members, each of said members provided at its ends with hinge loops and removable pins coperating with saidloops, and securing saidmembers together. V

7. Apparatus of the-class described including an investment holder comprising a perforated vertical wall outwardly flanged at its upper margin and a bottom plate conformed to provide ridges on its 'uppersurface and Ygrooves in its lower surface which",

plate to the central portion thereof.

' 8. Apparatus of the'class described comi l In witness whereof VI hereunto subscribe my name this 25th day of October, 1920.

y THOMASE. MOORE.

Witnesses:

` Z. O. RARRICK,

GUY T. FATHER.

kextend from the margins ofthe Vbottom v 

